Rick Gates, Paul Manafort’s former business associate is set to take the witness stand Monday afternoon in the bank fraud and tax evasion case against Manafort.

Rick Gates, the longtime deputy of former Trump campaign chairman Paul Manafort, is set to take the stand Monday afternoon in Manafort’s trial on charges of bank and tax fraud related to overseas earnings, a lawyer for Gates told POLITICO.

Gates is considered the star witness for the prosecution against Manafort — and his testimony in an Alexandria, Virginia courtroom is the first time he’s known to have faced Manafort since he agreed to cooperate with special counsel Robert Mueller’s team in February.